This watershed provides drinking water for much of
the San Francisco Bay area.
Except for occasional thunderstorms,
almost no precipitation falls from
May through September in the high
country. Both natural and human
communities depend on clean water
from the melting winter snowpack
during the summer months. To
protect Yosemite's water quality, the
National Park Service and the city
of San Francisco form a unique
partnership as steward of
the Tuolumne drainage.
Wildlife uses many behavioral strategies to survive
a long winter.
In heavy snow years, the ground
at this elevation may stay snow
covered for seven to eight
months. Some animals, like the
mule deer, migrate to lower
elevations. Others, like the
marmot, store energy in the
form of fat and sleep away the
winter in deep hibernation. Some
hardy animals stay active all
winter. They depent on
stored food, forage under
the snow in a network of
tunnels, or hunt and feed
during warm spells.